Hydraulic and geochemical interactions between surface water and sediment pore water in seasonal hypersaline Maharlu Lake,Iran

Study of interactions between surface-water and pore-water in lakes is complicated due to spatio-temporal heterogeneities in flow condition across the sediment–water interface. In this study, seasonal hypersaline Maharlu Lake was investigated by collecting surface-water and pore-water samples from four nests of multilevel piezometers installed at different distances from the inflow of rivers to the lake. The hydraulic heads in the piezometers as well as vertical profiles of Mg⁺², Na/Cl, and Br/Cl were used to investigate both hydraulic and geochemical interactions between surface-water and pore-water in the lake. Depletion of lake surface water and pore water with respect to B, Br, Li⁺, K⁺, Mg²⁺ and the absence of Mg-K chlorides and sulphates in the lake bed sediments is probably due to leakage of highly evaporated residual brine from the lake. Hydraulic gradients in the multilevel piezometric nests indicate that a general downward flow from surface-water to pore-water occurs across sediment–water interface. Vertical profiles of Br/Cl, Mg²⁺, and Na/Cl showed that the maximum flow rate was more than 1 m/yr close to the mouth of the inflowing rivers. The downward vertical flow was limited in the area far from the inflowing rivers due to the presence of an impermeable confining halite layer which interrupts the hydraulic connection between shallow pore water (less than 50 cm deep) and deeper zones. The hydraulic and geochemical interactions between surface-water and pore-water across sediment–water interface in the Maharlu Lake are of interest to find out the fate of pollutants and their distribution in the lake.     

Tectonic implication of geomorphometric analyses along the Saravan Fault: evidence of a difference in tectonic movements between the Sistan Suture Zone and Makran Mountain Belt

In this paper, remote sensing techniques,as well as field studies, have been used to investigate the geomorphological processes and landscape evolution along the Saravan Fault, SE Iran to highlight how topographic features were influenced by active tectonics. Quantitative geomorphic analysis was carried out using mountain-front sinuosity(Smf),valley floor width-valley height ratio(Vf), drainage basin asymmetry factor(Af), Hypsometric integral(Hi), drainage basin shape index(Bs), mean axial slope of channel(MASC), standard deviation of topography(STD) and index of active tectonic(Iat).Remote sensing techniques, as well as field studies revealed that the Saravan Fault have three parts trending N-S, NW-SE, and E-W. Obtained results show that basins with high Iat index are located at where the strike of the Saravan Faults changes and where several strike-slip faults are crossed the Saravan fault.     

Deformation analysis of the Lake Urmia causeway (LUC) embankments in northwest Iran: insights from multi-sensor interferometry synthetic aperture radar (InSAR) data and finite element modeling (FEM)

This paper presents deformation analysis of Lake Urmia causeway (LUC) embankments in northwest Iran using observations from interferometry synthetic aperture radar (InSAR) and finite element model (FEM) simulation. 58 SAR images including 10 ALOS, 30 Envisat and 18 TerraSAR-X are used to assess settlement of the embankments during 2003–2013. The interferometric dataset includes 140 differential interferograms which are processed using InSAR time series technique of small baseline subset approach. The results show a clear indication of large deformation on the embankments with peak amplitude of \(>\) 50 mm/year in 2003–2010, increasing to \(>\!\!80\)  mm/year in 2012–2013 in the line of sight (LOS) direction from ground to the satellite. 2D decomposition of InSAR observations from Envisat and ALOS satellites that overlap in the years 2007–2010 shows that the rate of the vertical settlement and horizontal motion is not uniform along the embankments; Both eastern and western embankments show significant vertical motion, while horizontal motion plays a more significant role in eastern embankment than western embankment. The InSAR results are then used to simulate deformation using FEM at two cross-sections at the distance of 4 and 9 km from the most western edge of the LUC for which detailed stratigraphy data are available. Results suggest that consolidation due to dissipation of excess pore pressure in embankments can satisfactory predict settlement of the LUC embankments. Our numerical modeling indicates that nearly half of the consolidation since the construction time of the causeway 30 years ago has been done.